This paper studies the graphemes <b> and <u,v> in a corpus of medieval Latin manuscripts from the 8th to the 12th centuries, containing texts by three His- panic writers: Isidore of Seville († 636), Braulio of Zaragoza († 651), and Ildefonso of Toledo († 667). The manuscripts written in Hispania are compared with those pro- duced outside the Iberian Peninsula to extract data about the graphic distribution of <b> and <u/v> in the textual transmission. After data annotation and statistical processing, the results are analyzed with two complementary objectives. Firstly, the mentioned graphemes are studied as evidence of the geographical distribution of the geographical distribution of the velar semiconsonant and the sonorous bilabial stop, and their Romance outcomes. Secondly, the results contribute to the phonetic and graphic characterization of Hispanic medieval Latin in the context of the emergence of Romance languages.